The invention relates to an apparatus for determining fibre lengths and fibre length distribution from a fibre material sample, especially in spinning preparation. In such apparatus, sample preparation elements may be located upstream of the measuring, evaluating and indicating device, said preparation elements comprising a clamping device and a combing element for the treatment of collected fibre material, the combing element producing a fibre fringe that is used for the measurement.
In the practical operation of spinning, fibre slivers taken from production are brought into a fibre laboratory, where the following testing is carried out:    (a) several slivers are placed by hand in clamps previously opened by hand and are carefully, that is, homogeneously, distributed across the width of the clamp and then the clamp is closed by hand.    (b) The fleece is clamped between two leather-covered plates. The plates are pressed into flat abutment with one another. There is no actually defined clamping point.    (c) The fleece is combed by hand using a single-row straight comb.    (d) A round brush is finally used to brush out the fibre fringe again.    (e) One side of the clamp is offered up to a fibrograph, then the clamp is turned over and the other side is offered up to the fibrograph. Using the fibrograph, two fibre fringes are transported past light sources. The source light passing through falls on light receivers and is registered and evaluated.
To test fibre slivers and flyer spinning frame slubbings, the leaflet “Fibrograph 630” of Spinnlab, Knoxville, Tenn., USA describes how, for preparation of a sample, the fibre material sample is opened and spread out and placed in a fibre clamp. The clamp members hold the fibres in their actual arrangement in sample zones. The randomly connected, overlapping, non-parallel relationship between the fibres remains as it is. When the sample has been thus prepared, the fibre clamp is placed in the fibrograph, which brushes out the fibre fringe, scans the sample optically and displays the result of the measurement.
The known sample preparation is time-consuming. Manual handling and processing of the sample and placing thereof in the measuring apparatus are additional to transportation from the spinning works to the test laboratory. It is a further disadvantage that owing to the individual handling of the sample preparation, the samples are not uniformly consistent. Finally, it is inconvenient that a fibre measurement at the location of the spinning machine is not possible.
It is an aim of the invention to produce an apparatus of the kind described in the introduction that avoids or mitigates the said disadvantages, and which in particular makes possible within a short time a sample preparation founded on an equal basis and allows an accurate measurement of the samples.